In recent years, much effort has been made to research quantum computers based on coupling between a cavity and physical systems arranged in the cavity. In such a quantum computer, the physical systems which couple to a common cavity mode of the cavity are used as qubits (quantum bits). The quantum computer executes calculation by resonating the qubits with the common cavity mode to generate an interaction between the qubits, and in that state, optically manipulating the qubits. For the quantum computer, there has been a demand to increase the success probability of optical manipulation of the qubits referred to as quantum gate operation.